Fat mice led David Hackam, director of pediatric surgery at Johns Hopkins, on a mission to find out why one group became obese while others on the same diet did not. The most recent study concludes that an interaction between genes, bacteria and diet is responsible, a finding that also has implications for obesity in people.

Hackam: We found that those bacteria that were found in these mice that are missing this gene break down sugars more readily. So they take starch, and the only way to digest starch in the human is to use bacteria to break it down, these bacteria are very efficient at breaking it down so they can feed themselves and they get very happy, but now, the host, the body, us, sees more sugar. So the same diet these bacteria, influenced by this gene, now creating a smorgasbord of extra food for the body. :31

Hackam says future studies will look at whether it is possible to eliminate these bacteria and stave off obesity. At Johns Hopkins, I’m Elizabeth Tracey.